title: Disrupted white matter in language and motor tracts in developmental stuttering.
abstract: White matter tracts connecting areas involved in speech and motor control were examined using diffusion-tensor imaging in a sample of people who stutter (n=29) who were heterogeneous with respect to age, sex, handedness and stuttering severity. The goals were to replicate previous findings in developmental stuttering and to extend our knowledge by evaluating the relationship between white matter differences in people who stutter and factors such as age, sex, handedness and stuttering severity. We replicated previous findings that showed reduced integrity in white matter underlying ventral premotor cortex, cerebral peduncles and posterior corpus callosum in people who stutter relative to controls. Tractography analysis additionally revealed significantly reduced white matter integrity in the arcuate fasciculus bilaterally and the left corticospinal tract and significantly reduced connectivity within the left corticobulbar tract in people who stutter. Region-of-interest analyses revealed reduced white matter integrity in people who stutter in the three pairs of cerebellar peduncles that carry the afferent and efferent fibers of the cerebellum. Within the group of people who stutter, the higher the stuttering severity index, the lower the white matter integrity in the left angular gyrus, but the greater the white matter connectivity in the left corticobulbar tract. Also, in people who stutter, handedness and age predicted the integrity of the corticospinal tract and peduncles, respectively. Further studies are needed to determine which of these white matter differences relate to the neural basis of stuttering and which reflect experience-dependent plasticity.
authors.affiliation: Department of Experimental Psychology & Oxford Centre for Functional MRI of the Brain (FMRIB), University of Oxford, South Parks Road, Oxford OX1 3UD, UK. Electronic address: connally@fmrib.ox.ac.uk.
authors.forename: Emily L
authors.initials: EL
authors.lastname: Connally
authors.affiliation: School of Psychology and Clinical Language Sciences, University of Reading, Earley Gate, Whiteknights Road, Reading RG6 6AL, UK. Electronic address: d.ward@reading.ac.uk.
authors.forename: David
authors.initials: D
authors.lastname: Ward
authors.affiliation: Cognitive, Perceptual and Brain Sciences Department, University College London, 26 Bedford Way, London WC1H 0AP, UK. Electronic address: p.howell@ucl.ac.uk.
authors.forename: Peter
authors.initials: P
authors.lastname: Howell
authors.affiliation: Department of Experimental Psychology & Oxford Centre for Functional MRI of the Brain (FMRIB), University of Oxford, South Parks Road, Oxford OX1 3UD, UK. Electronic address: kate.watkins@psy.ox.ac.uk.
authors.forename: Kate E
authors.initials: KE
authors.lastname: Watkins
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000375:Aging; D002531:Cerebellum / Q000473:pathology; D003337:Corpus Callosum / Q000473:pathology; D056324:Diffusion Tensor Imaging; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007802:Language; D008297:Male; D009044:Motor Cortex / Q000473:pathology* / Q000503:physiopathology; D009415:Nerve Net / Q000473:pathology* / Q000503:physiopathology; D010296:Parietal Lobe / Q000473:pathology; D011712:Pyramidal Tracts / Q000473:pathology; D012727:Sex Characteristics; D012737:Sex Factors; D013060:Speech; D013342:Stuttering / Q000473:pathology* / Q000503:physiopathology; D066127:White Matter / Q000473:pathology* / Q000503:physiopathology; D055815:Young Adult
keywords: Arcuate fasciculus; Fiber tracking; Fluency disorder; Posterior limb of internal capsule; Speech production; Structural image analysis